Soluble ostomy pouches are known in which the pouch may be discarded and dissolved (or dispersed) in the water of a common toilet bowl and in the discharge lines of a waste-disposal system. One type of such a pouch is constructed of a pair of side walls that are each composed of at least two layers, specifically, a tough, flexible, but water-soluble or water-dispersible primary layer, which gives the pouch its structural integrity and a thin, water-insoluble layer which lines the inside of the pouch and prevents the pouch's contents from contacting and dissolving the primary layer when the pouch is worn (see U.S. Pat. Nos. 4,772,279 and 4,917,689). Another type of known flushable pouch is at least partially formed of pH-sensitive material so that a basic or acidic agent may be added to the toilet bowl to initiate dissolution of the pouch (see U.K. patent application GB 2,201,372A and U.S. Pat. No. 4,629,999). While such pouches may be discarded in a toilet bowl and through the discharge lines of a water-disposal system, such constructions have not been entirely successful because of manufacturing complexities and user inconvenience. In particular, regarding the laminate construction of a water-soluble primary layer with a water-insoluble protective liner, manufacturing such a construction has proven to be difficult and problems may also be encountered with the water-soluble primary layer prematurely dissolving while the pouch is being worn. Regarding pH-sensitive pouches for which it has been proposed to add a basic or acidic agent to the toilet bowl to initiate dissolution of the pouch, it has been found that relatively large quantities of such agents are required to alter the pH of the water in the entire toilet bowl to the pH level required to disintegrate the pouch, and users of such devices find carrying such large quantities, in some instances of highly caustic material, inconvenient and possibly dangerous.
The present invention is concerned with a pouch constructed of pH-sensitive materials but, as mentioned, it is believed impractical, as in prior systems, to change the pH of the entire volume of water in a toilet bowl to a level sufficient to dissolve the pouch, as this would require the user to carry large quantities of acid-forming or base-forming agents which may be dangerous. Carrying such large quantities of pH-modifying material is inconvenient in that it requires the user to carry separate components and involves the additional step of adding that substance to the toilet bowl. Obviously, requiring the user to carry and add such pH-modifying materials, which may be caustic and dangerous, is contrary to the objectives of providing a convenient, toilet bowl disposable ostomy pouch.
An important aspect of this invention therefore lies in providing a self-contained, flushable, pH-sensitive ostomy pouch that includes its own pH-modifiers so that it will readily disintegrate when discarded in the water of a toilet bowl without requiring a user to carry and add additional components to the toilet bowl water to initiate dissolution of the pouch. Such an ostomy pouch comprises a pair of side walls joined together along their outer margins and composed of pH-sensitive material capable of dissolving when exposed to an aqueous fluid having a pH substantially above or below a neutral pH level. An external membrane is secured to the pouch and extends adjacent to at least one of the side walls to define a pocket therebetween. A quantity of pH-modifying material is contained in the pocket which, when exposed to a generally pH-neutral fluid entering the pocket, is capable of changing the pH of the fluid in the pocket to a level substantially above or below a neutral pH. If the pouch walls are sensitive to fluids of elevated pH and alkali-soluble, the pH-modifying material may take the form of a finely-divided, dry alkali material which is only relatively caustic and is fully hydrated so that it will not draw moisture through the external membrane when the pouch is being worn. Dry, finely-divided sodium metasilicate pentahydrate has been found to be particularly effective for this purpose. Alternatively, a tissue layer impregnated with such a dry base-forming material may be disposed in the pocket. Such a tissue layer is believed to be highly effective in enhancing the rate of dissolution of the pouch walls as its hydrophilic and absorbent nature, when exposed to water in a toilet bowl, tends to draw water into the pocket and maintain that water, of elevated pH, in close contact with the pouch side walls. If the pouch walls are sensitive to fluids of lowered pH, suitable acid-forming agents may be contained in the pocket or impregnated into a tissue layer disposed in the pocket.
The external membrane includes an entrance means for allowing aqueous fluid to enter the pocket and contact or dissolve the pH-modifying material when the pouch is discarded in the water of a toilet boil. Once the fluid entering the pocket dissolves or mixes with the pH-modifying material and attains an elevated or lowered pH, it initiates dissolution of the pouch by dissolving the adjacent pouch wall or walls such that the pouch loses its structural integrity and may be safely and effectively flushed away through the discharge lines of the waste-disposal system.
In one embodiment, the external membrane is composed of pH-sensitive material and the entrance means may take the form of a plurality of apertures in the membrane. A strip of removable adhesive tape is used to cover the apertures while the pouch is being worn, and a user removes the adhesive tape prior to discarding the pouch in the water of a toilet bowl. When the pouch is so discarded, aqueous fluid in the toilet bowl flows through the apertures and contacts or dissolves the pH-modifying material, which changes the pH level of the fluid now within the pocket to a level substantially above or below a neutral pH level. The fluid of altered pH then dissolves the adjacent pouch walls as well as the pH-sensitive external membrane.
In another embodiment, the external membrane is composed of a water-soluble polymeric material, such as polyvinyl alcohol, which is capable of quickly dissolving or dispersing in the water of a toilet bowl. Such a water-soluble external membrane acts as the entrance means for allowing aqueous fluid to enter the pocket because, when the membrane is exposed to water in a toilet bowl, the water will initiate disintegration of the membrane and enter the pocket where it contacts the pH-modifying material and attains an altered pH level. In a similar construction, the external membrane may be composed of a water-sensitive cellulosic material such as tissue paper which is capable of quickly dissolving or dispersing in the water of a toilet bowl. When the pouch is discarded in the water of a toilet bowl, the tissue paper allows water to pass therethrough and contact or dissolve the pH-modifying material in the pocket, which results in the fluid attaining an altered pH and dissolving the adjacent pouch walls. In such embodiments, the pouch is preferably contained in a soft cloth comfort pack while it is being worn to shield the water-soluble external membrane from direct contact with the user's skin; otherwise, moisture from the skin's surface might cause premature disintegration of the water-soluble membrane.
In some embodiments, it may be desirable to use a liquid as the pH-modifying material. Common basic or acidic liquids may be used but it is believed that liquid ammonia is particularly effective in such cases. In such an embodiment, the liquid agent is contained in a rupturable packet that is disposed in the pocket between the external membrane and the pouch side walls. The rupturable packet, preferably made of a foil material, includes lines of weakness which, when the packet is squeezed between a user's fingers, will rupture and thereby cause the liquid contained therein to be dispersed throughout the pocket. The pouch is then discarded in the water of a toilet bowl.
In the preferred embodiments, the pouch side walls are formed of alkali-sensitive materials, such as alkali-soluble carboxylated acrylic polymers, capable of dissolving when exposed to an aqueous fluid having a pH level higher than approximately 10. In such embodiments, the pocket defined by the external membrane and the pouch side walls acts as a means for localizing and concentrating fluid of elevated pH in close proximity to the alkali-soluble pouch walls so that only the fluid in the pocket must attain a pH level above 10 to result in dissolution of the adjacent pouch walls. Since the pocket has a relatively small volume of about 5 to 20 milliliters, preferably about 10 milliliters, only a minute quantity of sodium metasilicate pentahydrate or a like material is required to elevate the pH level of the fluid in the pocket to approximately 11 (the approximate pH level required to initiate dissolution of the pouch side walls). Such a construction is particularly advantageous as the user is not required to carry any additional agents or components to facilitate dissolution of the pouch and the pouch itself only requires a relatively limited amount of pH-modifying material to dissolve the pouch such that it may be safely and effectively flushed away through a toilet bowl and waste-disposal system.
Other advantages, features and objects of the invention will become apparent from the specification and drawings.